Inspection processes are used at various steps during a semiconductor manufacturing process to detect defects on a specimen such as a reticle and wafer. Inspection processes have always been an important part of fabricating semiconductor devices such as integrated circuits. As demand for semiconductor devices increase the need for improved device inspection capabilities will also continue to increase. However, as the dimensions of semiconductor devices decrease, inspection processes become even more important to the successful manufacture of acceptable semiconductor devices. For instance, as the dimensions of semiconductor devices decrease, detection of defects of decreasing size has become necessary as even relatively small defects may cause unwanted aberrations in the semiconductor devices. In another instance, existing inspection algorithms provide a relatively simple way to detect defects with a multiple channel system. However, since the existing inspection algorithm for the multiple channel system uses signal intensity, there are cases when defect count varies significantly due to changes in illumination light levels and wafer-to-wafer variation. The impact is to cause defect inspection to be less adaptive to illumination and wafer-to-wafer variations.
Therefore, it is desirable to provide a system and method that cures the shortcomings of the previous approaches.